Embodiments described herein relate generally to a laser welding apparatus and a laser welding method using the apparatus.
It is generally known that when a reactor structure or other members are damaged, repairs are made to restore soundness by using laser welding.
In an example of such laser welding, a large amount of gas is blown to around the portion to be melted to establish a locally dry condition in the water, and the dry metal surface is irradiated with laser light so that the base metal and the extremity of the welding wire are melted to mend the defective portion.
As disclosed in Japanese Patent Application Laid-Open Publications No. 2002-103077 and No. 2005-279720, the entire contents of which are incorporated herein by reference, there are known laser welding apparatuses that are capable of laser welding in the water.
In the laser welding mentioned above, it may be difficult to maintain a constant distance between the laser welding head and the portion to be welded in cases such as when the already-existing welded structure has a large error from its drawings, when the portion to be welded includes a curved surface, and when the portion to be welded has a difference in level. In such cases, there has been the problem that the laser welding head and the portion to be welded no longer have a stable positional relationship for high-quality welding.